1. Field of the Invention
The present invention relates to novel compounds which impart to foods a "thick, sour taste" even at neutral pH, compositions which contain such compounds, methods for preparing such compounds, and methods of flavoring food with such compounds.
2. Discussion of the Background
Natural extracts such as meat extract, chicken extract, extract of fishes and shells and vegetable extracts have been widely used commercially as basic seasonings of foods. It is considered that these natural extracts serve to give foods a complicated, deep, substantial taste, making up for an insufficient taste of certain food materials.
However, since these natural extracts are costly and hard to obtain, processed products and substitutes using a part of these natural extracts have been produced and marketed. Basic stocks of a dried bonito, dried small sardines, tangle and cortinellus shiitake and flavor seasonings obtained by adding salt, sugar, flavor, amino acids and the like to these natural materials have been also widely used. These commercial processed products and substitutes of the natural extracts are made up of low-molecular weight substances such as amino acids (mainly sodium glutamate), nucleic acids and organic acids. Accordingly, compared with the natural extracts, these are defective in that the taste is plain and flat. In order to improve this defect, a substantial, complicated taste has been achieved so far by adding hydrolyzed vegetable protein (HVP), hydrolyzed animal protein (HAP), yeast extract, and the like. However, HVP and HAP have an odor resulting from the hydrolysis, and the yeast extract has an odor peculiar to the yeast. Accordingly, the amounts of these materials used are naturally limited, and the resulting taste and flavor are clearly different from the natural extracts. Therefore, these materials are not satisfactory, especially with respect to the "thick, sour taste" and the "sharp, deep taste" by which the overall taste of foods is improved.